Hard disk drive manufacturing appears to have reached a physical limit of storage density in hard drives that store data using the perpendicular magnetic recording (PMR). In order to continue offering hard drives with increased storage capacities, hard drive manufacturers have begun to introduce hard drives that use storage formats other than PMR, such as shingled magnetic recording (SMR). SMR records data by partially overwriting previously recorded data. This allows SMR to offer higher storage capacities than PMR. However, due to the overlapping nature of data stored using SMR, write performance in SMR drives can be slower than in their PMR counterparts in some circumstances. In an attempt to mitigate the lower write performance of SMR, some SMR hard drives include fixed-size caches, where data is first written using a non-SMR storage format and then later moved to an area where it is written using SMR storage.